Bearing cooling device



April 17, 1951 W. L. CLAYTON BEARING COOLING DEVICE Filed April 17, 1947 Patented Apr. 17, 1951 UNITED stares param- OFFICE 2,549,171 BEARING COOLING n vIoE William L. Clayton, Harmony, Ba, Application April 17, 1947, Serial No. 742,189

b i 1 a This invention pertains to shaft and bearing cooling devices used in industrial heat treating devices such as annealing and heating furnaces, kilns andsimilar apparatuses in which a fan is rotated within by a shaft operatively connected to an outside drive,

- The methods of and apparatuses used heretofore for such purposes had the disadvantage that, due to the high temperaturesinside the heat treating devices, thedriving shaft of the fan conducted so much heat to the driving mechanism, especially to the shaft supporting bearings, that they were subjected to excessive wear, failure of lubrication and consequently an early breakdown.

v To alleviatethis disadvantage was proposed a to make the drivingshaft of the fan hollow and to employ blades thereon, to cause a flow of the atmospheric air partially through the shaft and partially outside of the shaft toward the heating device, these devices however, though diminishing somewhat the heat transmitted to the, drive by the shaftpwould not eliminate enough heat to obviate the troubles aforementioned,

. My invention eliminates entirely these and other disadvantages by providing suitable means to transmit to the atmosphere all harmful heat conducted by the dr v ng shaf of h f n from the heat treating device before the heat can reach tha part of thedriv which is s ppor in the bearin I a hiev this r lt y pl ying a fan driving f l adin from e inside of the heat treating device to the outside drive in several units, two of which at-least are separated by an air gap that is. brid ed o e by a coupling operating as a heat trap, which pres vents the heat to travel from one shaft unit to the adjac nt one. Thi he t t ap per tcs u h principl th h at lways flo s fr m. the pla or hi h r t mperature to th f l er temperature and never oppositely.

The invented structure causes the heat to flow to the low temperature peripheral portion of the coupling, from where it is transmitted to the atmosphere and cannot travel past the coupling to the abutting shaft unit. The eifect of this heat trap is analogous to a water trap which is connected to the sea level; hence the water will always flow from the higher level into the trap and from there into the sea and never in opposite direction. l

Hence, one object of the present invention is t provi a h at prote ted drive which will. pr vent the flow of heat from one shaft unit to an operatively connected abutting shaft unit by 1 Claim. (01. sos: 'z

, rigidly connecting them with on cou n com- Another object of he inven io is to rovi a, drive of the character described having shaft units divided by an air gap, and attached by a rigid coupling composed of two disks and of r latively thin con ecting blad re i ly large dimensions compar n t t e di m e of the shaft, whereby the rotary speed of the periphery of the coupling becomes; several times reater than that of it h b rt n- A fu th r o ct of t e nvent o is to p v d 7 r a heat protec e ri e empl i a c p in between. abuttingsha t un t whi c upl a ts as an impeller drawing the airthrough a hollow haft por ion eje t ng i adia yt us t impact with the connecting blades of the coup ns 1 Still another object of the invention is to provide a: rive shaf co d f t r n s.

the first reac i i o a heat t g ppa a and being solid or otherwise impassable to the heated gases he tmo he W n the heat treating chamber, the second shaft unit, being id y conne ed to the fir bc e ho11oW and provi ed. ith. a plur i y of openings to the ou side atmosphe e and ha n fast n to the end thereof the hub portion of a rigid coupling, the ec nd, hub rtion o which e n i i y connected to a third shaft unit supported in bearings and operatively connected to rotating ri e m ans,

Another objeot of the invention is to, provide a heat protected drive consisting of shaft units separated by a r sap id e o r by a r id oup in on i t g o di and nn ct n vanes which are cooled by air flow caused by the rotation of said shafting.

Yet another object of the invention is to provide a heat protected drive shaft, the separate units of which are connected by a coupling con struoted as a Centrifugal impeller, the blades of which are suitably curved for causing suction from its central part toward its periphery during its no at o v These and other object o th invention Will be e ide t to those e sed i he ou when read he foll w n c ifica i u i conn i i e ompanyns draw n in wh h:

Figure 1 is a semi-diagrammatic representation of a po i n. o a heat treating na e elevational cross soction wh ch a fan is rotated 3 by a shaft connected to a vertical outside drive, shown in elevational view.

Figure 2 is a cross-sectional view on line 2-2 in Figure 1.

Figure 3 is a cross-sectional view on line 33 in Figure 2.

Figure 4 shows a. second embodiment of the invention in'which a second impeller is interposed between the first and second shaft units, shown in cross-sectional view.

Similar parts are denoted by similar charac ters throughout the-several views of the drawing.

Referring now to the drawing by the characters of reference the heat treating device shown in Figure 1 represents an annealing furnace, gener ally designated by the numeral I into which fuel and air are introduced to the interior of the furnace by a nozzle I I for combustion. For uniform heat treating of the material (not shown) in the furnace the combustion gases are stirred by a-fan I2,-which is fixed to a rotary shaft unit I3, preferably of heat resisting material.

Shaft unit I3 traverses the wall I4 of furnace II) through a suitable aperture I5 which has sufficient clearance for frictionless rotation therein of shaft unit I3. A suitable stuffing box gland I6 of any approved type prevents the leaking out of the hot gases from the furnace. Shaft unit I3 is preferably solid or has closed ends thereby preventing the passage of hot gases or air through the shaft.

Shaft unit I3 is rigidly connected by conventional means such as a set-screw I! to coupling half I8 to which a corresponding coupling half I9 is fixed by suitable means such as bolts 20, or

otherwise. To coupling half I9 is rigidly attached a hollow shaft unit 2| by means of a set-screw 22. A plurality of holes 23 are provided in-the hollow shaft unit 2| through'which holes air can freely pass from the atmosphere into the hollow shaft portion.

At the other end or the hollow shaft unit 2|, which is away from the furnace I0, is fixed the and the radial diameter of which is also substantial, several times that of the outside diameter of shaft unit 2|. Disks 25 and 26 have a hub portion 21 and 28 respectively. Hub portion 21 is fixed rigidly by a set-screw 29 to hollow shaft unit 2| while hub portion 28 of disk 26 is fixed in a similar way by a set-screw 3|] to the third shaft unit 3|.

Between disks 25 and 23 are vanes 32, shown to be curved impeller blades, suitable to draw air from the'central portion and to draw it peripherally, when rotating.

Shaft unit 3| is supported by bearings33 secured in any approved manner to a stationary support 34. Driving means such as, for instance, a pulley 35 is fixed to the shaft unit 3| and operatively connected by means of a belt 36 to the driving pulley 31 fastened to the shaft 38 of a prime mover 39, shown to be an electric motor. While for the sake of simplicity of the drawing I have shown only a single drive for a single fan 7 Motor 39 rotates pulleys 35 and 31 by means of the belt 36 thereby rotating the shaft unit 3| supported in bearings 33, and together with it also of the coupling 24.

shaft unit I3 and the fan I2. From the furnace Ill heat will be conducted by shaft unit I3 to coupling halves I8 and I9 from which the heat will proceed through the hollow shaft unit 2| to hub 21 of disk 25. Simultaneously impeller vanes 32 set up arapid flow of air through the hollow shaft unit 2|. As indicated by the arrows, the atmospheric air enters through holes 23 and flows axially toward the vanes 32 after which it is expelled radially by them due to the suction and compression respectively, that the vanes 32 create.

It is to be noted that all the sucked-in air moves axially within the hollow shaft in a direction away from the furnace and is expelled radially by the vanes 32 between the disks and 26 This air stream takes by conduction and convection part of the heat flowing in hollow shaft unit 2| while part of it will travel toward hub.2I of the disk 25 heating the hub section'first, then progressing toward the periphery of the disk 25. The outside surface of disk 25 is in contact with the atmosphere and is effectively cooled thereby,

' The cooling effect increases from'the by conduction and convection.

V hub portion toward the periphery because the rotary speed of the disk particles increase from the hub portion toward the periphery and with it is increased the relative speed difference between the atmospheric air particles and contacted disk particles, hence, also the amount of heat given from the disk particles to the atmosphere. In other words, the temperature of the disk particles will decrease from the hub toward the periphery. Another cause for the temperature drop'toward the periphery of the disk is that the mass and the surface ofthe disk in every circular crosssection increases from the hub toward the periphery. I

As a consequence, at suitable rotary speeds of the disk 25its peripheral portion will have a considerably lower temperature than its hub portion 2?, hence, the heat conducted by the shaft unit 2| will constantly and quickly travel from the hub portion 2! toward the place of the lowest temperature, which is the peripheral portion of the disk 25. v

The vanes 32 are effectively cooled by the air stream they'produce and which they contact on both sides of their impeller surfaces. 7 Very little heat will be transmitted to disk '26 by the produced air stream because of the small relative speed difference between the air particles of the air stream and that of the contacted particles of disk 26. Similarly very little heat will be given by-the air stream to the hub portion 28 and shaft unitl3l, for the same reason. ever heat is transmitted by the air stream and by the vanes 32to disk 26, it will be effectively dissipated through the cooling effect of the atmosphere in a similar way as it was described in connection with disk 26. Also here the peripheral portion of disk 25 will have the lowest temperatur'e, hence, the heat will flow from the hub por-' tion away from the shaft unit 3| toward the peripheral portion of disk 26. As a result, the shaft unit 3| will show only a negligible increase in temperature, hence, its supporting bearings and other driving parts will be protected efiec-' tively from the heat coming from the furnace I0.

Whatever was said as to blocking the heat conducted by shaft units I3 and 2 I, is true as to the heat possibly radiated from the furnace toward the bearings which are shielded effective- However, what- 7 1y from the radiated heat through the substantial dimensions and mass of the heat dissipating coupling 24, interposed between the bearings and the furnace.

Figure 4 represents the second embodiment of my invention which differs only in that respect from the first embodiment that between shaft units 13 and '2 I, which both are partially hollow and are provided with a plurality of radial holes, a second heat dissipating coupling 2% is installed instead of the rigid coupling halves i8 and is shown in the first embodiment. Ihis second coupling 24 may be constructed from parts of similar or different dimensions than the parts of the first coupling to suit conditions. The heat blocking effect of each of these couplings is a function of the masses and outside diameters of the shaft units and of those of the disks 25 and 26 and also of the thickness, of the width and of the shape of the vanes 32 and of the speed at I.

which they are rotated including the heat conducting characteristics of their materials and also of the atmospheric temperature and of the temperature prevailing within the chamber of the heat treating device. These variables being known in each instance by suitable selection of the materials and proper. dimensioning of the parts, which is only a matter of skill, by applying the principles and structure I invented, and disclosed hereby, for every purpose and installation a perfectly suitable heat protected drive or bearing cooling'device, as my invention is entitled, can be constructed by those versed in the art.

The second embodiment functions in a similar manner as the first one except that the conducted and radiated heat will be blocked from entering the next shaft unit at two locations instead of at a Single one, such as shown in the first embodiment.

Having fully disclosed my invention and illustrated it by two embodiments, it will be under 7 stood that various changes and modifications may be made within the scope of my invention, hence I do not wish to be limited by these exemplary embodiments.

I claim:

A hearing cooling device to be interposed between a heated shaft unit and a bearing comprising a pair of shafts at least one of which is hollow and adapted to be fastened to the heated shaft unit in axial alignment, a pair of radially disposed spaced apart discs of relatively large diameters and masses as compared with the shaft unit, impeller vanes connecting the discs, said discs and vanes connecting the pair of shafts at a spaced apart position from the junction of the hollow shaft and heated shaft, lateral openings in the hollow shaft between the junction of said shaft with the heated shaft and the radially disposed discs, and openings connecting the interior of the hollow shaft and the space between the radially disposed discs for drawing air out of the hollow shaft.

'WILLIAM L. CLAYTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Busquet June 28, 1949 

